This invention relates to an applicator to which a highly viscous fluid to be applied such as a correction fluid, a make-up fluid, an adhesive and a paint is charged.
In an applicator having a spherical form of application member (application ball), a tip is attached to the neck formed at one end of a fluid tank which is filled with a fluid to be applied, and the tip bears rotatably therein an application ball in such a way that the application ball may partly be exposed from the front edge thereof like a ballpoint pen. The application ball is resiliently urged by a spring so as to bring the application ball into intimate contact with the caulked front edge of the tip, whereby to allow the application ball and the front edge of the tip to form a valve structure, preventing the fluid to be applied from being discharged, when the applicator is not used.
When the application ball is pressed against a surface to be treated for application of the fluid, the application ball retracts against the resilience of the spring to provide a clearance between the application ball and the front edge of the tip, allowing the fluid deposited to the hidden portion of the application ball locating within the tip to be delivered through the clearance to the outside of the tip for application as the application ball is rolled. However, since the fluid has high viscosity, the fluid cannot normally be fed fully to the surface of the application ball. Accordingly, the fluid tank is molded by blowing using a flexible material to be squeezable, and the fluid tank is pressed between the fingers to increase the internal pressure of the fluid tank for application of the fluid to allow the fluid to be fed to the surface of the application ball with the aid of the thus increased pressure.
Meanwhile, in the case where the application member is rod-shaped, a tapered portion is formed at the middle of the application member, and the tapered portion of the application member being resiliently urged by a spring is brought into intimate contact with the caulked front edge of the tip to form a valve structure between the rod-shaped application member and the front edge of the tip, so that the fluid to be applied may not be discharged. When the application member is pressed against the surface to be treated, the application member retracts against the resilience of the spring to provide a clearance between the tapered portion of the application member and the front edge of the tip. Then, the fluid tank is pressed between the fingers so as to increase the internal pressure of the fluid tank, and thus the fluid is fed to the application member and can be applied to the surface to be treated.
As described above, the prior art applicators are inconvenient and troublesome to use since the fluid tank must be pressed between the fingers to increase the internal pressure of the tank for application of the fluid, and besides the production cost elevates since the fluid tank must be molded by blowing using a flexible material.
Therefore, if a cap is designed to be able to be push-fitted to the neck of the fluid tank with the front edge of the tip being sealed with the inner barrel of the cap and to reduce the volume of the sealed space defined within the inner barrel, in the process that the cap is engaged with the neck, the internal pressure of the inner barrel can be increased. Accordingly, the air in the inner barrel enters into the fluid tank to increase the internal pressure of the fluid tank, and thus the fluid tank need not be pressed between the fingers for application of the fluid to be applied.
However, since the application ball is resiliently urged by the spring, the application member must be retracted against the resilience of the spring so as to allow the air in the inner barrel to enter into the fluid tank. Accordingly, the internal pressure of the inner barrel must sufficiently be increased. In other words, while the push fitting stroke of the cap in the state where the inner barrel thereof is sealing the front edge of the tip must be increased, the longer the inner barrel of the cap becomes, the more difficult and inconvenient the pressurizing operation, becomes.